Cities have always been the engines of economic growth; now they hold the key to a sustainable future. Cities today have a unique opportunity to become global engines of green growth by choosing energy-efficient... Show More + solutions for their infrastructure needs.The urban arena is where development challenges and solutions meet. 6.2 billion people—or two-thirds of the world’s population—will be living in cities by 2050. Unfortunately, most of this urban growth will take place in developing countries, where the vast majority of people remain unserved by basic infrastructure services and where they are least able to cope with the uncertainty of climate impacts. Right now in developing countries nearly one billion people are living in slums.Today, cities account for roughly two-thirds of the world’s overall energy consumption and about 70 percent of global greenhouse gas emissions. This past summer, the concentration of carbon dioxide in the atmosphere passed levels not seen in three million years. Show Less -